DE268890C

DE268890C -

Info

Publication number: DE268890C
Application number: DENDAT268890D
Authority: DE

Description

KAISERLICHESIMPERIAL

PATENTAMT.PATENT OFFICE.

PATENTSCHRIFTPATENT LETTERING

- JVl 268890 .-' KLASSE 21g·. GRUPPE- JVl 268890 .- 'CLASS 21g ·. GROUP

SIEMENS & HALSKE AKT.-GES. in BERLIN.SIEMENS & HALSKE AKT.-GES. in Berlin.

Verfahren zur Messung der Härte von Röntgenröhren.Method for measuring the hardness of X-ray tubes.

Patentiert im Deutschen Reiche vom 22. November 1912 ab.Patented in the German Empire on November 22, 1912.

Unter den Methoden zur Bestimmung der Härte von Röntgenröhren spielen heute immer noch diejenigen Methoden die Hauptrolle, bei welchen die Absorption der Röntgenstrahlen in Metallen verschiedener Dicke zur Messung benutzt wird. Härtemesser dieser Art sind abei nur in der Nähe der Röhre anwendbar; sie gestatten nicht eine objektive Beobachtung und sind zur fortlaufenden KontrolleAmong the methods for determining the hardness of X-ray tubes are always playing today nor those methods in which the absorption of the X-rays plays the main role is used for measurement in metals of various thicknesses. Durometers of this type are aei can only be used in the vicinity of the tube; they do not permit objective observation and are for continuous control

ίο der Härte nicht geeignet.ίο not suitable for the hardness.

Es sind auch Einrichtungen zur direkten Anzeige der Härte bekannt geworden, welche eine objektive Ablesung an einem von der Röntgenröhre entfernten Ort gestatten und in einem Spannungsmesser bestehen, der entweder die der Röhre aufgedrückte Spannung mißt oder einpolig an die Kathode der Röntgenröhre angeschlossen ist. Doch sind die Angaben solcher Härtemesser nicht einwandfrei, weil die Messung der Röhrenspannung stets indirekt und daher nicht fehlerfrei geschieht. Insbesondere sind die Angaben des an die Kathode der Röhre einpolig angelegten Elektrometers wenig zuverlässig, zumal die in diesem Falle gemessene Spannung durch die Röhrenspannung durchaus nicht eindeutig bestimmt, sondern von der Aufstellung der Röhre, d. h. dem elektrischen Potential der in der Nähe der Röhre befindlichen Körper abhängig ist.There are also devices for direct display of the hardness are known which allow an objective reading at a location remote from the X-ray tube and consist in a voltmeter that shows either the voltage applied to the tube measures or is unipolarly connected to the cathode of the X-ray tube. But they are Details of such hardness meters are not correct, because the measurement of the tube voltage always happens indirectly and therefore not error-free. In particular, the information provided by the Electrometer applied unipolarly to the cathode of the tube is not very reliable, especially since the in In this case, the voltage measured by the tube voltage is by no means clearly determined, but on the placement of the tube, d. H. the electrical potential of the bodies in the vicinity of the tube is dependent.

Den Gegenstand der Erfindung stellt- ein Verfahren für die Härtemessung dar, welches eine direkte Ablesung und fortlaufende Aufzeichnung der Röhrenhärte an einem von der Röhre beliebig entfernten Orte gestattet. Sie beruht darauf, daß man die Dichte des Gas-40 The subject matter of the invention is a method for hardness measurement which allows direct reading and continuous recording of the tube hardness at a location that is as far away as you want from the tube. It is based on the fact that the density of the gas 40

inhalts der Röntgenröhre, welche bekanntlich ein Maß der Röhrenhärte darstellt, unter Anwendung eines direkt zeigenden Gasdichtemessers mißt.content of the X-ray tube, which is known to represent a measure of the tube hardness, using a direct pointing gas densitometer.

Besonders geeignet sind hierfür Widerstandsdrähte aus Metall, welche in dem zu messenden Vakuum angeordnet und von einem elektrischen Strom durchflossen .werden. Die Temperatur solcher stromdurchfiossenen Drähte hängt ab einmal von der zugeführten Wärme, d. h. also von der durch den Strom erzeugten Jouleschen Wärme, und zweitens von der abgeführten Wärme. Die Ableitung der Wärme geschieht auf dem Wege der Strahlung, der Wärmeleitung des Gases und der Konvektion im Gase. In der Reihe dieser drei Faktoren spielt im vorliegenden Fall die Leitung vermöge der geringen Gasdichte eine so untergeordnete Rolle, daß von ihr ganz abgesehen werden kann. Wesentlich sind hingegen die Strahlung und die Ableitung durch Konvektion. Während von diesen erstere von der Gasdichte unabhängig ist, ist letztere und demzufolge die gesamte Wärmeableitung mit der Dichte des Gases veränderlich. Also stellt die stationäre Temperatur des im Hohlraum der Röhre befindlichen und von einem konstanten Strom durchflossenen Leiters eine Funktion der Gasdichte, also auch eine Funktion der Härte der in der Röhre erzeugten Röntgenstrahlen dar. Die Härtemessung ist also gemäß der Erfindung auf eine Temperaturmessung zurückgeführt.Resistance wires made of metal, which are in the to be measured, are particularly suitable for this A vacuum is arranged and an electric current flows through it .be. the The temperature of such wires through which current flows depends on the supplied heat, d. H. that is, from the Joule heat generated by the current, and secondly from the heat dissipated Warmth. The heat is dissipated by means of radiation, heat conduction of the gas and convection in gases. In the present case, management ability plays a role in the series of these three factors the low gas density plays such a subordinate role that it can be completely disregarded. On the other hand, they are essential Radiation and its dissipation by convection. While of these the former of the Gas density is independent, is the latter and consequently the entire heat dissipation with the density of the gas is variable. So it represents the stationary temperature of the cavity of the tube and through which a constant current flows Function of the gas density, thus also a function of the hardness of the generated in the tube X-rays. The hardness measurement is therefore, according to the invention, a temperature measurement returned.

Die Temperaturmessung an dem stromdurchflossenen Leiter kann auf verschiedenen Wegen direkt und indirekt erfolgen. So kannThe temperature measurement on the current-carrying conductor can be on different Because of direct and indirect. So can

Claims

they are done in such a way that the electrical line resistance of the current-carrying conductor or that of another conductor heated by this is measured. One can also determine the temperature of the conductor with the help of thermocouples in a bolometric way, i. H. by measuring the thermal radiation emanating from the body through which the current flows, and also optically ίο. The drawing shows an exemplary embodiment of a device for carrying out the method and two types of circuit therefor. In the arrangement according to FIG. 1, an attachment tube a is located on an X-ray tube R, which contains a resistor b, suitably made of thin wire. This connecting piece is provided at such a point that the resistor is not hit by either secondary cathode rays or secondary X-rays and receives as little radiant heat as possible from the anticathode and the warm parts of the tube wall. The extension tube α is expediently surrounded by an X-ray impermeable material, e.g. B. made of lead glass. The resistance of the wire is determined by simple current measurement in a circle containing the resistance wire b with a current source β of constant voltage and otherwise always the same resistance. In the circle there is also a known resistor w and an ammeter m. You can also use the resistor w to regulate the current strength and determine the resistance of the wire using a voltmeter. The resistance b must have the smallest possible heat capacity, because the smaller it is, the faster it will assume the steady-state temperature corresponding to the respective gas density and the smaller the measurement errors when measuring rapidly changing hardness. A more sensitive circuit is shown in Fig. 2, where a Wheatstone bridge circuit is indicated. The resistance wire b is here in a branch of the bridge. Any of the known circuits for measuring the temperature by means of resistance wire can be used here. A thermocouple can also be used to measure the temperature and thus that of the hardness, the hot soldering point of which is arranged on the resistor or in its immediate vicinity. The measuring device used to measure resistance and temperature is expediently calibrated in any known units of hardness, e.g. B. according to Benoist-Walter, Wehnelt or according to the absorption that the X-rays experience in lead sheet, the thickness of which increases by V10 mm. Godfather nt-A ν Proverbs:

1. A method for measuring the hardness of X-ray tubes, characterized in that that the temperature in the cavity, which varies with the gas pressure in the tube of the tube and constant rms value of an electric current or applied to a voltage with a constant rms value Conductor or a physical variable that changes with the temperature of the conductor (electrical resistance, amperage, voltage, emissivity of the conductor) is expediently measured by means of electrical measuring methods.

2. Device for performing the method according to claim 1, characterized in that that the measuring conductor is located in a side tube communicating with the X-ray generation area, and that this is arranged as far away as possible from the parts of the X-ray tube that heat up during operation, that the measuring conductor is neither from X-rays nor from secondary cathode rays is hit.

1 sheet of drawings.